This relates in general to mechanical seals between fixed and rotating bodies, and more particularly to self-aligning pump seals.
In pumps and other types of machinery in which it is necessary to provide a seal between a rotating shaft and non-rotating portions of the housing in which the shaft rotates, problems arise because of inital structural imperfections, uneven junctions and wear and tear on structural parts, all of which tend to cause constant misalignment between the non-rotating and rotating elements.
Various methods of solving these problems have been proposed and implemented in the prior art by providing for relative motion in an axial direction between a non-rotating ring, which is constantly floating or self-adjusting, relative to a rotating member fixed to the rotating shaft. These prior art self-adjusting means have taken various forms, such as providing spring-bias between the non-rotating and rotating elements, or interposing a resilient ring, or a flexible metal ring, between the non-rotating and rotating members. None of these devices has been found to be fully satisfactory in providing constant full-face, fully lubricated contact between the rotating and non-rotating members. Thus, initial maladjustments, and wear between the parts is not fully compensated by these prior art devices, thereby causing leakage around the seal and requiring constant replacement of the parts.
Accordingly, it is the principal object of this invention to improve the sealing means between non-rotating and rotating elements in pumps and other types of rotating machinery, more particularly by providing self-adjusting means which are not subject to constant readjustment or replacement. Other objects of the invention are to provide self-adjustment and/or self-alignment means for the stationaries of pump seals and the like which are simpler, more effective, and less expensive to install and maintain than those available in the prior art.
These and other objects are achieved in accordance with the present invention in an improved seal assembly, more specifically, comprising improvements in the stationary composite of the seal assembly, which comprises a pair of rings disposed in coaxial, colinear relation, adapted for installation in an annular recess in a cylindrical gland, or other element secured to the housing in which a pump shaft or other rotatable device is journaled to rotate. The composite stationary comprises a first metal ring, which is seated against the inner wall of the gland recess, and held in place in the recess by a peripherally-disposed O-ring, and has a U-shaped cavity filled with viscous liquid which accommodates telescopically an inwardly-directed annular stub of a second ring. The latter is directed in an axial direction to project into, and form, with O-ring contacts, inner and outer seals against the walls of the U-shaped annular cavity of the first metal ring. An anti-rotational pin may be provided to prevent rotation between the first and second rings. The annular outer face of the second ring, which is normal to the axis of the shaft, provides a smooth surface against which the rotor attached to the shaft bears in sealing relation during rotation. Viscous liquid interposed into the U-shaped cavity of the first ring acts as a buffer, permitting the first ring to float, constantly adjusting its position in an axial direction as the shaft rotates.
A particular feature of the invention is that the liquid, which may be, for example, silicone jelly, is easily injected into or removed from the annular cavity of the first ring through small bores, which are readily sealed up. The liquid may either be interposed freely into the annular cavity, or it may be enclosed in a flexible toroidal tube which is interposed when the rings are assembled to form the cavity.
These and other objects, features and advantages of this invention are better understood by a study of the detailed description hereinafter with reference to the drawings.